The invention relates to metering and packaging machinery for bulk particulate or flaked dry material.
Vertical form, fill and seal machines are used for a wide variety of products, ranging from foodstuffs to soaps and cleansers. In essence, these machines take a ribbon of bag material on a roll, wrap it around a hollow tube, and form a seal running longitudinally to make a hollow film tube. The tubes are formed around a vertical column with a hollow interior through which the material being packaged is introduced. A heating apparatus at the bottom seals the tube to close it at one end. After the longitudinal seal has been formed and the transverse seal at the bottom made, the bulk material being packaged is introduced into what is now a tube with a closed end. Once the appropriate amount of material has been introduced, the tube is pulled downwards (or the heating bar is moved upwards) and the bottom portion of the tube with the packaged bulk material is sealed at the top. Once sealed, a cutter cuts off the lower portion of the tube with the material sealed inside and the bag produced thereby is released into the remaining part of the manufacturing process where it is typically placed in a box and then in a case for shipping.
Each of these machines is quite expensive. As a result, they are operated as fast as possible. This, in turn, requires a steady stream of measured volumes of bulk material to be packaged. Traditional methods of volumetrically measuring bulk material have not been satisfactory with these high-speed machines. For that reason, it has been the practice to use a multiple bin feed system called a combination scale. In these systems, many hoppers are simultaneously and continuously fed from a single material source. A computer control system measures these hoppers, and opens the hopper or hoppers having the appropriate amount of material. Since the feed rate cannot be controlled with any precision, there are typically fifteen to twenty of these hoppers that are simultaneously fed. With that number of hoppers being simultaneously fed and weighed, it is generally true that at least one hopper (or a combination of two or more hoppers) will have the appropriate amount of material to fill the bag every time a new portion of bulk material is required.
These combination scale feeding systems, however, are expensive. Since every hopper has its own electronic measuring device, and since there are so many hoppers required to ensure that one or two of them will have the right quantity of material, they are very complex, very large, and very expensive. Changing from one material to another material requires an extensive down time in which the fifteen or twenty-five hoppers are cleaned and sanitized.
What is needed therefore is an improved system for volumetrically measuring and metering bulk materials that operates at high speed. What is also needed is a system for volumetrically measuring and metering such material and subsequently individually packaging such material in a form fill machine that is more compact, less costly, and easier to use than the previous system. What is also needed is a system that will sequentially and alternately release volumetrically measured quantities of bulk material from a plurality of weigh buckets. It is an object of this invention to provide such an apparatus.